Signal light



April 15, 1941. w. LINTERN ET'AL S IGNAL LIGHT Filed Dec. 31, 1938 2 Sheets-Sheet 1 INVENTORS WILLIAM LINTERN &

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WILLIAM A. LINTERN V THEIR ATTORNEY.

April 15, 1941. w. LINTERN ETAL SIGNAL LIGHT Filed Dec. 51, 1958 2 Sheets-Sheet 2 INVENTORS WILLIAM LINTERN & WILLIAM A.LINTERN THEIR ATTORNEY.

Patented Apr. 15, 1941 tern, Brook Park Village, Ohio, assignors to 'ljhe Lintern Corporation, Cleveland, Ohio, a corporation of Ohio Application December 31, 1938, Serial No. 248,786

6 Claims.

This invention relates to an improvement in signal lights of the type used for example to indicate emergency exits, fir"e extinguishing equipment, danger points of indoor and outdoor tratfic routes-etc. and'ior conveying. definiternessages of any desired nature;

Such signal lights should be so constructed that light displayed by them will be clearly visible from as many directions asrequired by'their specific uses. One of the objects o'f'the present invention is to amplify the visibility range of signal lights, particularly in planes along which the signal is most likely to be viewed, but without critically reducingthe visibility range when viewed along other planes.

Another object is to provide animproved pris: matic lens of the generally cylindrical type adapted to enclose and protect alight source and which is arranged to expose mag'nifiedimages of said sourcesharply and clearly to view all around the light source, particularly at anglesnearly normal to the lens axis and radiating fromthe center of such source, but with sufiicient clearness for practical signaling. purposes at all other angles about such center and passing through exposed wall portions of the lens.

Another object is to provide an improved means for conveying self-explanatory messages or legends in conjunction with amplification of visibility range of a light source as outlined above.

Specific objects include the provisions "of anof mounting'for the various parts and a'visibility (light curve) diagram also being shown on the vieWjFig. 2 is a full longitudinal sectional view ofthe lens, showing at one side the manner in which" light rays are projected from-the lens at various angles and'at the other side the angular relationship. of reflecting and refracting prisms of the lens wall; Fig. 3 is a partial sectional view showing a modified means for displaying a legend on the lens;and 4 is a side elevation of the lens showing. the manner in which the light sourceis displayed at one angle of view.

Referring to Fig. 1 a suitable mounting Iior" the n light bulb 3m'ay" compriseametai casting or stamping which ishollow'arid has-tatlet openings 5 and 6, variously arranged to receive su'ppo'r'ti'n'g or con uctor-carrying'pipes; one such being shown at I entering the'uppr opening which ma be threaded 00' receive the pipe. mounting maybegratly'riiodified'. A's shown the I'nOllrltiIlg lids a nang'esat its-10Wf filfl, against which a flange" 9oi the'le'ns" may removably secured, a gasket Ill being interposed which" is operable as" a seal and to reduce likelihood of fracturing of the lens whenthe same is made from glass, as preferred. A lens attaching ring I2' encloses the flange 9o f' the' lens and the ring" and flange 8* can besec'ured by bolts" I3 which,

pass through" notches-or holes in" the flange of the lens.

The lens, which is of generally cylindrical 'form and closed" at the end opposite themounting; can

\ be disposed inany conoeivable position,but tor illustration and purposes of des'criptiony'it' will be assumed that thelens' hasitscentral axis positioned vertically; The lamp (light source) is} maintained by its socket and the" attachment of the latter (not showm to the' nioun'ting l in such position that the effective center' offthe filamentor' incandescent element is approximately atthe position indicated by the circle L'on Fig. 1 The lamp can occupy other positionsfmoved up or down) depending on the expected average angle of view with respect to'the longitudinal axis of the lens. However, in the normalpositioning-of the lamp filament or incandescent element such as-V in Fig. 2, (representing a low. wattage 'va'p'o'r lamp) the center of radiation of light is'opp'osite an annular prismportion I5' of the lens located at a portion of the lens which, exclusive" of the prisms, issubstantially cylindrical; Above the" prism I5 is a prism=I6 having amajor face'jsom'ewhat broader than that-of the prism I 5. The angular relationships of the prism faces are" shown at the right of Fig. 2 and these angles and their functions will be referred to later'herein.

Above prism I6 are two or more" narrower prisms I1 and land, above these; the lens can be smooth and nearlyicylindrical, as at I9 both' insideand outside forthe purpose of efiectivelydisplaying a legend, as will later be des cribed;

or there can be a plurality ofprisms on the order of I! and I8 if' no legendis to be displayed: Below the prism I5 the lens, (exclusive of prisms thereon) becomes spherically'convex and the'annular prisms on the convex or globulargpqrtion ofith'e lens are indicated at 20, 2i, 22, i13,;2 gi,;2 5, zsand 21, respectivelyl 'Ihe'faces on oneside of the apices or'tnepnsmb (generally above the apex in each case) are indicated as at IBa, Ila, etc. and those faces below the apices are indicated as at IBb, Ilb, etc.

The angularity of the prism faces is fully described. on Fig. 2 at the right and, for convenience, these angles are related to horizontal planes, i. e. normal to the axis of the lens. The angles may vary a few degrees, say within a total of five degrees and the number of prisms may, of course, be greater or less than as shown.

Specific attention is called to the angularities of prisms I5 to I8 and 20 to 23 which are the most important from a practical standpoint because these are the prisms which are desired to become effective to display imagesfio'f the light source at longest range and through a fairly wide vertical angle. Display of such images is less important generally endwise of the lens because with the axis of the lens' extending ver-' tically (as usual) it is practically never very far to the limit of the distance fromwhich the signal can or need be observed.

' The prism face I5a is at a slight angle to the opposite inside face of the lens (about 4 as shown) and the broad area of this portion exposes the image of the filament or incandescent element through a considerable vertical angle. Similarly the prisms I6 and and to a diminishingextent the other prisms between I8 and 23, by reason of the angularity of the relatively broad faces of the prisms shown, expose images of the filament through wide vertical angles such that persons viewing the signal light from well above. and well below the horizontal plane of the light source, see the filament image either on a major or minor face of each of the prism mentioned. v

Summarizing the. above described arrangement of the more important outer prism surfaces in terms of convergence upwardly or downwardly, it will be seen that complements ofthe angles shown at the right on Fig. 2 give the following: The relatively broad surface I5a converges upwardlyat 8; the surface IBa at 44, and the surfaces Ila andIBa. at 90 and 104, respectively. Also the surface 20b converges downwardly at 48; the surface 2Ib at 92; 221) at 120, and 23b at 150". It can also be observed from Fig. 2 that the faces I6a, Ila and I8a successively increase in convergence upwardly and successively decrease in width upwardly, and that the surfaces 201), 2Ib, 22b and 23b, part of which lie on the globular portion of the lens, successively increase in convergence downwardly and, generally speaking, increase in breadth downwardly. This successive increase in angle of convergence upwardly and downwardly as to the respective prism surfaces ,.just mentioned and the relationship of breadth of the respective prism surfaces has been found to amplify the light source as observed from points generally at right angles to the lens axis and in the approximate elevation of the central prism I5 about as illustrated in Fig. 4.

The result is that throughout the critical vertical angle range for practical signalling purposes, observers see the filament image multiplied or amplified on the lens as a broad, nearly continuous, band of light. The light direction lines at the left on Fig. 2 indicate the vertical amplitude of the various prisms in transmitting the incandescent element images. The relationship of the image transmission properties of the various prisms to each other requires no specific description inview of the diagram.

When using a watt clear bulb having a conventional filament, the light strength of the signal throughout a range of is as shown by the light curve C on Fig. 1, wherein the extent of any one portion of the curve from the center of radiation of light indicatesin candle power-the signalling strength of the light at the angle of view of that portion about the center of radiation of light. For illustration, viewing of the light at 90 from the vertical axis affords a candle power of 469 as indicated and the candle power at close range and at 10 intervals is as marked at 80; 75 at 70 etc.).

Now, by using a low wattage vapor lamp with a disc-like incandescent element (V in Fig. 2) which is preferably illuminated on both sides of the disc, top andbottom in the position shown, solid, generally elliptical images appear on the major faces of the prisms, with the result that a much stronger signal effect is obtained than with the'ordinary glass globe or lens and much higher wattage bulbs with conventional filaments. Fig. 4 illustrates the above, the light spots on the black field being the reflected images as they appear at about six feet from the lens (point of view at level of prism I8).

Referring further to Fig. 2 and particularly the lines at the left of the view, it is apparent that the image of the incandescent element will remain visible on the face I5a. of the prism I5 through the angle included by the lines a and b indicating resultants of refraction of the lens; that the image on face IGa' of prism I6 will be visible through the angle represented by lines, 0 and d; on Ila by the angle represented, at e and f and on I8a. by the angle represented at g and h. Thefrelative angles of the prism faces and inner lens wall are such that at various elevations of the pointof view above and below the horizontal plane of the light source one is certain to be within several of the included angles described, from b to if at any appreciable distance from the signal light and will see the incandescent element image sharply defined in several places on the lens.

At higher elevations, one sees the image on faces I5a, 20a, 20b and 2Ia, 2Ib, etc., as will be clear from the diagram without specific description. The lowest elevation served by the lower prisms down to 23 is indicated by the line a, but at such elevations one would also see the image of the incandescent element on faces I 5a, IBa and possibly others. The image displaying angles of the lowermost prisms are also indicated on Fig. 2 by relatively radiating lines (not indicated by any characters). "The light curve on Fig. l is indicative of the candle power value at different angles of view generally endwise of the lens.

The preferred manner of displaying legends is by means of a detachable mask 35, the cylindrical portion I9 of the lensand a conical or globular reflector 36 inside the lens. The mask is cut out as at 38in the manner of a stencil so that'rays from the light source are projected by therefiector through the letters or symbols of the legend in generally diverging arrangement as indicated conventionally at the left of Fig. .2. The mask can comprise an extension of the attaching ring I2 previously described, or detachably mounted on the signal light in any other appropriate fashion s'othat one legend can readily be substituted for another at any time. The

reflector should have a stippled or crinkled s'ur face to diffuse .the lightgenerally and distribute Another way of displaying a legend is shown by Fig. 3 wherein indented portions 40 of the lens wall portion l9 delineate the legend or symbol areas which are transparent or translucent. Surrounding these areas, as between parallel concentric ribs 42, the lens can be rendered substantially opaque as by black vitreous enamel 43 applied during formation of the lens generally. The same or a similar arrangement of symbols and opaque background can be made integral with the lens but on the outside of it if desired.

We claim:

1. A signal light having a lens comprising a hollow translucent body of generally cylindrical form and substantially closed at its lower end by a globular lens portion, and adapted to enclose an incandescent element so that its center of emanation of light is located in a plane near the lower limit of the cylindrical portion, prisms on the cylindrical wall including an annular wall' portion opposite said element center, the outer surface of which wall portion converges upwardly at a relatively narrow angle, annular outer surfaces nearly normal to the lens axis adjacent said wall portion above and below it, a broad outer prism surface adjacent to the upper abrupt surface and converging upwardly at approximately 44, a less broad outer prism surface adjacent the lower abrupt surface and which converges downwardly at approximately 48, narrower annular prisms above the upper broad surface and with outer face surfaces which converge at increasing angles upwardly, and annular prisms below the said downwardly converging surface, outer faces of which latter prisms converge downwardly at increasing angles.

2. The arrangement of lens according to claim 1 wherein the outer surface of the annular wall portion opposite said element center converges upwardly at approximately 8.

3. The arrangement of lens according to claim 1 wherein the prism surfaces below the surface which converges at approximately 48, converge, in succession, downwardly at approximately 92, 120 and 150.

4. The arrangement of lens according to claim 1 wherein the prism surfaces above the surface which converges upwardly at approximately 44, converge, in succession, at approximately 90 and 104.

5. A signal light having a lens comprising a hollow translucent body of generally cylindrical form and substantially closed at its lower end by a globular lens portion merging with the cylindrical portion, and adapted to enclose an incandescent element so that the center of emanation thereof is located in a plane near the lower limit of the cylindrical portion, annular prisms on the cylindrical wall portion including a prism with a slightly upwardly converging relatively broad annular outer surface located approximately in the plane of said center, other annular prisms thereabove and therebelow on the cylindrical portion, separated from the first described prism and from each other by abrupt relatively narrow surfaces which converge toward points near said center of emanation, said other prisms which lie above the first described prism having outer relatively broad faces but of successively decreasing width upwardly and successively increasing angle of convergence upwardly, and those lying below the first described prism being carried partly on the globular portion and having outer relatively broad surfaces which are generally of successively increasing width downwardly and of successively increasing convergence downwardly.

6. A signal light according to claim 5 wherein there is an additional series of annular prisms on the globular portion with downwardly slightly converging outer faces which successively decrease in convergence downwardly, separated by upwardly widely converging outer surfaces, the width of each of which is about the same as the face of the slightly downwardly convergent face to which adjacent.

WILLIAM LINTERN. WILLIAM A. LINTERN.

CERTIFI GATE OF CORRECTION;

Patent No. 2,258,u95 April 1 19in WILLIAM LINTERN, ET AL. It 'is hereby certified that error appears in the printed specification orrection as follows: Page 5, first "annular" insert -abrupt; and 11 therein of the above numbered patent requiring c column, line 27, claiml, after the word that the said Letters Patent should be read with this correctio that the same may ponform to the record-of the case in the Patent Office.

Signed and sealed this 27th day of May, A. D. 19141.

Henry Van Arsdale, v

(Seal) Acting Commissioner of Patents. 

